Weak orientation and direction selectivity in lateral geniculate nucleus representing central vision in the gray squirrelSciurus carolinensis

Abstract

Zaltsman JB, Heimel JA, Van Hooser SD. Weak orientation and direction selectivity in lateral geniculate nucleus representing central vision in the gray squirrel Sciurus carolinensis. J Neurophysiol 113: 2987-2997, 2015. First published February 25, 2015 doi:10.1152/jn.00516.2014.-Classic studies of lateral geniculate nucleus (LGN) and visual cortex (V1) in carnivores and primates have found that a majority of neurons in LGN exhibit a center-surround organization, while V1 neurons exhibit strong orientation selectivity and, in many species, direction selectivity. Recent work in the mouse and the monkey has discovered previously unknown classes of orientation-and direction-selective neurons in LGN. Furthermore, some recent studies in the mouse report that many LGN cells exhibit pronounced orientation biases that are of comparable strength to the subthreshold inputs to V1 neurons. These results raise the possibility that, in rodents, orientation biases of individual LGN cells make a substantial contribution to cortical orientation selectivity. Alternatively, the size and contribution of orientation-or direction-selective channels from LGN to V1 may vary across mammals. To address this question, we examined orientation and direction selectivity in LGN and V1 neurons of a highly visual diurnal rodent: the gray squirrel. In the representation of central vision, only a few LGN neurons exhibited strong orientation or direction selectivity. Across the population, LGN neurons showed weak orientation biases and were much less selective for orientation compared with V1 neurons. Although direction selectivity was weak overall, LGN layers 3abc, which contain neurons that express calbindin, exhibited elevated direction selectivity index values compared with LGN layers 1 and 2. These results suggest that, for central visual fields, the contribution of orientation-and directionselective channels from the LGN to V1 is small in the squirrel. As in other mammals, this small contribution is elevated in the calbindinpositive layers of the LGN motion; thalamocortical; thalamus; striate cortex; area 17; lateral geniculate body; lateral geniculate bodies

The homotopic connectivity of the functional brain: a meta-analytic approach

“…Moreover, the noradrenaline released by LC is involved in working memory 187–190 and in increasing the signal/noise ratio in primary sensory cortices 191–197 . Other strongly co-activated areas are the following: medial and the lateral geniculate bodies, which have auditory 198–202 and visual 203–205 functions, respectively; the substantia nigra, which is well known for its role in motor control 206–210 but has been also thought to be implicated in cognitive activity 211–213 ; and several regions of the cerebellum, which, too, are supposed to be involved both in motor and in cognitive functions 214–220 , such as executive control, working memory 221–225 , and attention 226,227 . The cognitive role of these medial subcortical regions may suggest that, during the performances of tasks, they should be functionally active, so as to have more local connectivity and, therefore, more HC.…”

Predictive coding with neural transmission delays: a real-time temporal alignment hypothesis

“…This requires firstly that information about rate-of-change be represented and available at each stage. It is well-established that velocity is explicitly represented throughout the early visual hierarchy, including the retina 40 , LGN [41][42][43][44] , and 11 primary visual cortex 45 . As required by both models, velocity information is therefore available throughout the hierarchy.…”

An evolving view of retinogeniculate transmission

“…Recent work is revealing new receptive field complexity and plasticity in the dLGN that further demonstrates significant thalamic processing of visual information en route to the cortex, at least in some species. Stimulus orientation selectivity is one salient example of a complex feature encoded in subpopulations of dLGN neurons in a variety of species: mouse (Marshel et al, 2012; Piscopo et al, 2013; Scholl et al, 2013; Zhao et al, 2013) and rabbit (Levick et al, 2010; Hei et al, 2014), with weaker orientation or direction bias occurring in the cat (Hubel & Wiesel, 1961; Daniels et al, 1977; Levick & Thibos, 1980; Vidyasagar & Urbas, 1982; Soodak et al, 1987; Shou & Leventhal, 1989; Thompson et al, 1994), squirrel (Zaltsman et al, 2015), and primate (Lee et al, 1979; Smith et al, 1990; Cheong et al, 2013). Complex feature selectivity persists in TC neurons after inactivation of the primary visual cortex, suggesting that the dLGN may compute orientation or direction selectivity rather than inherit it from cortical feedback (cat Vidyasagar & Urbas, 1982; mouse Zhao et al, 2013; Scholl et al, 2013).…”